Honestly I’d recommend trading one of the lifesteal buffs for an Envenom Weapon. Makes it so your kingsbane literally one shots everything and the 2nd lifesteal just becomes a wasted card after buffing with the first. Sure having 2 makes you more likely to get it, but the deck has plenty of draw to ensure you get through the deck fast enough to get both.

I usually always have one Eviscerate in this deck, it’s great in the end if you’re playing against for instance Even warlock and you’re in the fatigue game and he just played Gul’Dan. He is most likely gonna be low and then you can deal 8 damage in the face to him (with the help of valeera). I removed Ooze for an eviscerate and it worked really well.

Greenskin is one of the most powerful cards in the list. You CAN play without it, but realistically you want it pretty badly.

Ranking up with the list is very meta dependent. It has good matches against combo and control, but terrible matches against aggro. There is a lot of aggro on the ladder typically, so personally I found it undesirable to ladder with.

Once you hit legend, the aggro drops a little bit, so maybe then you can rank up the legend ranks with Kingsbane.

I personally added one lab recruiter to the deck, as it allows to go infinite also with weapon buffs. Valeera > one weapon buff minion, lab recruiter on that minion, lab recruiter on lab recruiter. One needs to be careful though, because kingsbane could be at the bottom now. For more safety one could first only lab recruit on an empty board and put in 3 of them. and only once the deck is empty, use them from the hand to put copies of other minions in your deck.
Just an idea. Defeats the mirror match and adds some flexibility (need more vilespines? more minstrels? more faldoreis? shinyfinders because enemy runs 100 weapon removals?), but also some liability, as it does not do much and can also keep you from reaching important cards…